Help me eliminate strong fuel vapors in garage
 

Some of you may have followed my earlier post about buying a new 1969 c10 250 last week.

Prior to my ownership, the truck sat for over a decade. I have the truck parked in my garage now and there’s one problem. The gas vapors are overwhelming and begin to creep into the first room of the house adjacent to the garage.

So the first thing I’m planning on doing is addressing that. Here is what I see:

a.) Gas cap rubber gasket is cracked. I have a new gas cap on the way.

b.) The short piece of soft fuel line between the tank hardline and the fuel pump is very soft/worn. I picked up a piece of 5/16” soft line with clamps and will replace that

c.) I see that there is a small fuel leak at the carb. I’ve ordered a carb rebuild kit to try to address that (pic below).

Other than that, I don’t see any obvious leak. Additionally, I don’t detect any fuel vapors inside the cabin (source of smell is external).

Are there any other areas I should be looking at that are common sources of fuel vapors that I should also check on?

I’ll start with a/b/c above and report back how things are looking.

Thank you!

Re: Help me eliminate strong fuel vapors in garage
 

1969 trucks vented the carb and fuel tank to atmosphere, so there will be a slight fuel odor even if everything is new and tight. 1970 10 series trucks with RPO NA9 evaporative emission control and 1971-72 10 series used a sealed fuel system where fuel vapors were stored in a charcoal cannister, then eventually burned when the engine was running.

Re: Help me eliminate strong fuel vapors in garage
 

Thank you for pointing that out.

Although some vapors are expected given the ‘69 design, it seems it’s way excessive.

With a visible leak, I should probably address that before reaching any conclusions.

Re: Help me eliminate strong fuel vapors in garage
 

For what it's worth I had an almost new fuel pump (maybe 20 miles on it) weep gas around the cap where it was pressed together. Truck had been sitting in the garage for maybe a month since the last drive. Started leaking all of a sudden and filled the garage with fumes. Wasn't leaking enough gas to drip. Probably what I deserve for buying a cheap fuel pump. I enjoy changing a fuel pump on a 350. NOT! Something else to check. Good luck.

Re: Help me eliminate strong fuel vapors in garage
 

There is another short piece of rubber fuel line between the frame and the hard line under the rear of the cab. I recommend replace that since you're replacing the one at the fuel pump. Don't just go out there and squeeze it unless you have a new one ready, or a bucket to put under it and wrench ready to loosen the hard line at the sender, or it might crumble in your hands and accidentally siphon all the gas from the tank onto the ground.

And there is a rubber seal between the fuel sender and the tank, which you can get to by moving the seat forward. The fuel sender is near the top of the tank behind the seat. After removing the fuel line and electric wire from the sender, turn the lock ring counter clockwise. There is a special tool sold to turn that ring, but I simply used some large pliers with jaws open to press against the tangs to loosen and tighten that.

howzzzit mentioned the fuel pump itself, and there is rubber inside it. If the rubber in it is old it could be it was not the type of rubber that tolerates ethanol. Newer formulations of rubber must be used with gasahol. I bought a Delphi cheap fuel pump at Autozone and it has lasted about 5 years now, and I use gasohol, so I think it has the right rubber in it. There are problems with new fuel pumps that I have seen posts about on the forum about them failing fast, and some producing too much pressure and causing carbuetors to flood. So approach fuel pump problems with a little caution and if you install one you don't necessarily get to think you're done with that.

I have a 69 that I park in the garage and it doesn't have strong fuel smell so I think you are heading toward a solution. Be careful, and keep a fire extinguisher handy, and a buddy present and standing by if possible, while working on fuel stuff. And perhaps work on it outside.

Re: Help me eliminate strong fuel vapors in garage
 

Helpful feedback, thank you

Hmmm, if I break that soft line connection, I can’t see losing more fuel than was in the lines to start right? I mean the fuel in the tank needs to make its way up through the sending unit so I struggle to see any siphoning effect being possible?

Re: Help me eliminate strong fuel vapors in garage
 

The fuel will already be in the section of line coming up out of the tank from the last time you drove it, so it will indeed siphon. You can disrupt the siphoning from happening if you loosen the hard line from the sender before you remove the flexible line from under the cab. Same thing goes for the flexible line at the fuel pump.

Re: Help me eliminate strong fuel vapors in garage
 

Yes it'll surprise you and start siphoning right away and rather fast unless you open the hard line at a point higher than the level of fuel in your tank.

Re: Help me eliminate strong fuel vapors in garage
 

I'd definitely change that stuff outside, especially if you have a gas hot water heater or clothes dryer in that garage. Be careful. ;)

Re: Help me eliminate strong fuel vapors in garage
 

Thanks all, I’ll be sure to brake the hardline connect at the tank before replacing the soft lines.

One thing I do notice is that the rubber pass-thru grommets on the valve cover are badly worn (these are the inlets of the air tubes off the carb). Can those lead to a strong gas smell as well?

Re: Help me eliminate strong fuel vapors in garage
 

Sure, definitely replace those, they're well overdue. Careful, don't wanna' drop a piece in your valves. If I were you I'd replace all fuel, vapor, and vacuum hose. Short perhaps A/C hose through the cab.

Re: Help me eliminate strong fuel vapors in garage
 

I had a chance to get under the truck and did a bit of investigation.

- there’s no fuel smell inside the cabin
- the short stretch of soft line between the tank and the hardline under the cabin looks to be in good shape, no leak there.
- hardline under the truck looks fine.

- now the soft line leading up to the fuel pump is in terrible shape… very old and soft. There’s evidence that there was a leak under the fuel pump at least at some point. I’ll replace that soft line as soon as possible and I’m thinking maybe I should replace the fuel pump too for good measure. You can see there was a leak under the fuel pump (could be that soft line or it may be the pump weeping)? I ran my hand under the fuel pump, brought it up to my face, and it was strong scent of raw fuel.

How involved is a fuel pump swap in one of these 250s? I see the are pretty cheap on RockAuto.

Re: Help me eliminate strong fuel vapors in garage
 

That like appears to be dry as a bone. It's probably leaking if it's wet underneath. But you could inspect the pump underside with a mirror, for verification. Pump is a piece of cake. Have you downloaded the manuals yet?

Re: Help me eliminate strong fuel vapors in garage
 

That like?

You can see the rust spot where the fuel was leaking (at least at some point)

Will DL the manual

Any tricks to the mechanical armature positin being in the right position ?

Re: Help me eliminate strong fuel vapors in garage
 

Now is the time to fix the whole fuel system and you don't want to do it twice or your garage will smell like gas

There is a bolt at the front of the engine that will keep the fuel pump shaft from falling out while you r working on it

Re: Help me eliminate strong fuel vapors in garage
 

I thought that was only for v8?

Re: Help me eliminate strong fuel vapors in garage
 

Did not need "like" :lol:
Also, there is a low section of the cam that, if you get to it, makes pump installation easier against the lower spring pressure.

Re: Help me eliminate strong fuel vapors in garage
 

Run your finger under the flange where the pump is pressed together. That's where mine leaked on a new pump.

Re: Help me eliminate strong fuel vapors in garage
 

Will do. Just ordered a replacement Delphi fuel pump on RockAuto for $11. Did I mention I love the parts pricing on this truck (at least compared to my Lexus and my Wife’s Land Rover)

Re: Help me eliminate strong fuel vapors in garage
 

This applies only to SBCs.. The OP's engine is a 250 I6..

Re: Help me eliminate strong fuel vapors in garage
 

All I can say is good luck. When I put the 292 in mine in place of the 250 I figured I'd replace the pump just because. That was a mistake. The new pump would flood the carburetor out. When I checked the pressure it was running 7 1/2 at idle and more like 9 at higher RPM. Max fuel pressure on these 6s is either 3 or 3 1/2 I forget which. I returned that pump & used the old one off my 250.

Re: Help me eliminate strong fuel vapors in garage
 

Sorry I'll play my old grey card

Re: Help me eliminate strong fuel vapors in garage
 

What brand pump was that ?